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I have tried keeping my chubby plecos in couple of different tanks and I haven't been pleased with the outcomes. I have lost half of them and feel that they are breathing faster then they should be. I have a 26 bow that is growing out a lei arowana which should only take bout one or two more months until he is too big for the tank. Once he is out I want to try four chubbies in there. How does this sound to try and maximize the oxygen in the tank: I have an renz xp1 with a spray bar and AC 70 running right now. I was going to do a power head with a venturi but after reading past oxygenation/aeration threads worry about the heat. I was going to do a whisper 60 air pump with two 4 inch disc to produce bubbles. Do you think this will work. I know a wider shallower tank would be more ideal but this is my only spare tank and they don't seem thrilled in my125 right now.

why not do a wavemaker/koralia and have the bubbles feed into the pump. Just a thought. BTW, the wave makers give off a ton less heat.

I have a "venturi" pump going in my bar 125 to shoot the Co2 around in the tank.. not sure if i am doing something wrong, but t he plants are doing great and all the fish are healthy.

Won't the heat from the pump just mean the heater doesn't have to work so hard?

Jools

Jools wrote:Won't the heat from the pump just mean the heater doesn't have to work so hard?

Jools

If the pump is in the water, it will

I got a tank with a 38 watt pump in the innerfilter, and this tank does not require any heating - there is no even a heater inside - in order to remain 3 C above ambient temperature.

Obviously, it is a tank for fish from fast moving water, and these waters are alwauys rather cold - so this 3 degrees centigrade are quite sufficient. And as I did require the watrermovement, the heat is basically for free

Bas Pels wrote:Obviously, it is a tank for fish from fast moving water, and these waters are alwauys rather cold

Huh? It's frequently well above 30C in the rapids of the rivers where fancy plecos are collected (Xingu, Tocantins, Tapajos etc).

I thought were thermophiles.

Part of the reason I worry about heat is because my place gets really warm in the summer. Typically my apartment gets in the mid to low 80s and the tanks can get up to 90. Want to maximize oxygen with minimizing additional heat. Plus the hotter the water the less oxygen it will hold.

Most of the year I don't need to plug my heater in

The airstones will be your best bet for incresing O2 levels without raising the tank's temperature.
-Shane

Shane wrote:The airstones will be your best bet for incresing O2 levels without raising the tank's temperature.
-Shane

great thanks. Does that sound sufficient with the dual air pump and my two filters? I could always do the powerhead as well for added current but feel that maybe over kill

The Rena XP1 is rated at 250 gph and the Aquaclear 300 gph (those numbers are best case with clean intakes and media). Alone those two filters are considerable turnover for a 26 gallon tank.
-Shane

@Racoll, you are right. That tank is for Central American fishes, and in CA this is more or less the case.

In South America the Rio Xingu (and probably others) has rapids and slow parts which succeed each other, being ~the same temperature.

I was thinking CA. And Europe.

Hi all,

The airstones will be your best bet for incresing O2 levels without raising the tank's temperature.

I think air stones are always a good idea, but a "wet and dry" trickle filter would be even better. Wet and dry trickle filters are much more effective at both gas and heat exchange than any other method of filtration or oxygenation.

Having said that I agree with Barbie, the Arowana worries me, and maintaining high dissolved oxygen levels is often much more to do with biological filtration rather than direct aeration. We have an article on dissolved oxygen <http://www.planetcatfish.com/shanesworl ... ved+oxygen> that Shane wrote, and I'd definitely recommend reading it.

Also with apologies for the cross-post, but I wrote this article specifically to deal with the problems of keeping rheophilic fish with a high oxygen demand in warm water: "Aeration and dissolved oxygen in the aquarium" <http://plecoplanet.com/?page_id=829>. It covers much of the same ground as Shane's article, and has many of the same conclusions, but adds some more detail.

The basis for it came from work we did in the lab. on the treatment of "landfill leachate", a fairly nasty effluent with a huge BOD.

cheers Darrel

Very nice article Darrel.
-Shane

I use Eheim Aquaball1212 powerheads in all my hypancistrus breeding (and non breeding as well) tanks. Temperatures usually run 80° plus in these tanks. Don't know if the Aquaballs help, but my fish and my plants are healthy (Knock on wood !) Good luck.

From Darrels article one could conclude that it is better not to use much wood in a rheophilic tank. That is correct, but there is another reason.

Biomass will - ultimately - dissolve and produce humus acids. These are a nice foodsource for bacteria, which is in the most cases no problem, but rheophilic fishes are not used to water with much humus dissolved - and might, therefore, be sensitive towards them, resulting in illneses

I keep my rheophilic tanks free from wood, and see the fish thrive. Before I had to be carefull with deseases, now it is much better.

Anotherthing is, again I read an airstone does not diffuse much oxygen. Personally, I think this is an urban myth. Clearly, any individual bubble does not exist for a long time. BUT on any time, the tnak does contain, say, a few huyndred individual bubbles, which each diffuse a little oxygen.

Assuming one has 500 bubbles on any given time, each 1 mm diameter (that is 1/24th of an inch). Wikipedia tells me ths sufvace is 4*pi*r2. That is 0,03 square centimeter per bubble or 15 square centimeters (~2.5 square inches) for 500 bubbles.

These bubbles start in the lowest part of the tank, where the oxygen levels are lowest.

The rate of diffusion equals the concentration difference, and therefore thes 15 square centimeters will, effectively, diffuse much more oxygen than 15 square centimeters on the surface.

I can also observe: The same amount of flow, made with a machanical pump does not help the fishes as well as made witrh airstones.

Airstones work better, because they ALSO diffuse

I am curious about one issue here with airstones. Doesn't the temperature of the air going into the pump determine the temperature of the air being released into the tank. If the ambient temperature is 90F would this not mean one is pumping 90 degree air into the water. Now if the water itself is less than 90F, would not the warm air bubbling up though that water act to heat that water to some degree?

I know that filters and power heads etc. will all heat the water to some degree. I assume an air pump also generates internal heat and this could also serve to warm the air a bit too?

Hi all,

Very nice article Darrel

Thank you, I hope it is useful to people.

I wrote it originally after talking to a couple of Bristol based L. number breeders, "thegeeman" <http://www.planetcatfish.com/forum/view ... =5&t=30987> and particularly the late Bob Marklew "Macvsog23" <http://www.planetcatfish.com/forum/view ... 23#p209044>.

They have/had years of experience of fish keeping/breeding and Bob was probably the most clued up and perceptive fish keeper I've ever met. The genesis of the article was that they had both experienced unexpected sudden L. number deaths, where a fish that had been healthy had suddenly been found unmarked, and still apparently healthy, but dead.

They'd discounted fighting etc and were really at a loss for a cause.

Bob had a huge amount of biological filtration (Eheim canisters and Alfagrog "refugiums") and water movement in his tanks (in a warm fish house), and was a fanatical water changer (mix RO/tap), he didn't have any plants in the L. number tanks (although he had other planted tanks). After talking we decided that the only factor that the deaths had in common was that it was nearly always the largest fish in the tank that had died.

After some thought it came to me that the most likely option (only option?) was a fall in dissolved oxygen levels, and that was why it was always the largest fish that died. After some further investigation we came to the conclusion that the most likely cause of lowered oxygen levels was emergency chloramine dosing of the tap water after water main work, and that the small additional amount of ammonia was enough to tip the DO levels over the brink. Bob started using RO and HMA, and added floaters (Limnobium etc) to all the tanks, which seemed to have worked, but tragically died before any firm conclusion could be made. I really miss him.

I use Eheim Aquaball 1212 powerheads in all my hypancistrus breeding

I like Aquaballs as internals as well (I have an internal and an external on all tanks larger than 60 litres if I can't have a trickle filter), partially because they keep running, and the venturi still works, when they need a clean (I use both Aquaballs and MicroJet powerheads with a coarse PPI10 sponge pre-filter).

There are some heat and Maxijet bits here, with "Apistomaster"'s photos <http://www.planetcatfish.com/forum/view ... 8&p=227740>.

One advantage of an exposed sponge pre-filter is that you can aim the venturi bubbles from outflow at the sponge of the other filter, and bubbles will be retained on the sponge surface. This hopefully ensures that the water entering the filters is as fully oxygenated as possible.

When I came back to fish-keeping I was amazed that people were using their filters as syphons, and didn't have a pre-filter, and all the filtration talk was about how often to change your floss, which filter media to use and volume of the canister, but nobody was talking about oxygen. It is all about oxygen, everything else is just froth.

one could conclude that it is better not to use much wood in a rheophilic tank..... These are a nice foodsource for bacteria, which is in the most cases no problem, but rheophilic fishes are not used to water with much humus dissolved - and might, therefore, be sensitive towards them, resulting in illneses

I like to keep the tank water BOD as low as possible, but I have wood in all the tanks <http://www.planetcatfish.com/forum/view ... 30#p245019> and I'm not convinced by the "low in humic compounds" argument. The reason is that (nearly?) all the water courses with L. numbers in them must also contain woody debris in their quieter stretches, and humic and tannic compounds must be continually flushed through-out the white and clear water rivers, as well as more obviously in black water rivers.

Anotherthing is, again I read an airstone does not diffuse much oxygen. Personally, I think this is an urban myth. Clearly, any individual bubble does not exist for a long time. BUT on any time, the tnak does contain, say, a few huyndred individual bubbles, which each diffuse a little oxygen..... I can also observe: The same amount of flow, made with a machanical pump does not help the fishes as well as made witrh airstones.

You are definitely correct, but I think it is quite a minor effect. I like a lot of bubbles, they certainly can't do any harm.

This is from "Aeration....

The bubble size is also important, in that the smaller the bubble the greater its relative surface area is, and the more diffusion of gas into the water will occur. What you do have to remember is that air is only 21% oxygen, and oxygen is much less soluble in water than, for example CO2. This means that an air pump needs to produce very fine bubbles (in the range of 10 – 200 microns diameter), that have a long “residence time” in the water column, if significant exchange of oxygen to the water is to occur. For maximum residence time and effect, ....... it would be advantageous if the filter intake picks up both the bubbles and oxygenated water, and feeds them straight into the filter where they will provide much needed oxygen to the nitrification process.

Diffusers and bubbles
Ceramic flat plate diffusers are one possibility for producing fine bubbles, and they are widely used in aquaculture, they have the disadvantages of being expensive, requiring high air pressure and clogging relatively easily. The other option is a membrane diffuser, which has the advantages of not clogging so easily and requiring lower air pressure. The technical term to look for is “EPDM“ (ethylene propylene diene terpolymer), and the membrane diffuser can be in the form of a disc, tube or “air wall”. These kinds of diffuser are widely used in the waste water industry, and in aquaculture, where the BOD of the water may be several hundred times the waters natural oxygen holding capacity.

The actual effect of bubbles is quantified in thread somewhere on PC, but I can't find it. I think it has content from both "Mats P" and "Jools", can any-one find it?

cheers Darrel

Hi Thank you for all of the input

There are no parasites. I have a good quarantine procedure and they were treated appropriately with the prazi. Furthermore the rest of the tank mates (L14s, panda uarus ,gold severum, cloud archers) are fine.
The tank has a three inch leichardti arowoana right now and the fish is by itself. As I write the current chubbies are in a 125 and the 26g will be its future tank. None of my tanks have any ammonia and nitrite and all having varying levels of low nitrates. I do twice a week 30-40% wc. I have seen chubbies for sale at multipe shops and I have never seen then have what i would consider a normal resp rate for other plecos. I really think it is O2 dependent.

I have also read Darrel's article and all related before posting.

Thanks for the input. To summarize this is not a water quality or parasite issue. The fish are currently in a 125g and will be moved to the 26 once it has been freed up

I use these with the matching weights that slip on the tubing. I create a bubble wall along the back of the tank, with an air pump good for a 100G on my 75G. No muss no fuss with suction cups, the weights eventually sink into the sand leaving the tubing lying on top. Creates a beautiful effect with both large sand small bubbles. Plus my corys love playing in the bubbles. Please excuse the tinted water having a bit of an algae issue.

Hi all,

I have seen chubbies for sale at multipe shops and I have never seen then have what i would consider a normal resp rate for other plecos. I really think it is O2 dependent.

I'm sure you are right, and that it is an oxygen issue, they are a fish that have a high oxygen demand and in stressful conditions this requirement will become even higher.

not one of my tanks have any ammonia and nitrite and all having varying levels of low nitrates. I do twice a week 30-40% wc.

I understand what you are saying, but I'm not a great believer in the results you get from test kits. I'm not against the idea of testing, far from it, but the problems really are to do with test kits and how reliable their results are.

Personally I wouldn't try and keep any fish with high demands on water quality without either plants or a trickle filter, and ideally both. Some people can maintain high quality water purely by water changes, but I need all the help I can get.

cheers Darrel

this has turned out to be an interesting thread. I will let everyone know how it plays out.

Seems like stating the obvious, but keeping the tank clean will help a lot in keeping DO levels up. If you have two inches of gravel (like so many aquarists have!), then small bits of food and faeces will slowly accumulate and suck up oxygen as they decompose. Better to have a thin layer of grit/sand, and vacuum regularly. Much cleaner this way.

Same goes for filters. Regularly clean them. I noticed my L260s were breathing heavily last night. I suspect it's because I've been feeding them a lot recently, and not cleaned the filter in a while.

Barbie wrote:Prazi is totally ineffective against Ich, chilodonella, and oodinium. All of these can exist with no external symptoms, causing quite a bit of stress to the fish due to gill damage. Oodinium especially just suffocates fry as they finish absorbing their yolk sacs, with absolutely no external signs. Without a microscopic evaluation of the newly dead fry, I would not have known either. How exactly are you determining that your quarantine procedure is adequate?

We have a local shop that regularly told people that their fish deaths were due to low dissolved oxygen in their saltwater systems. It took a year or so of me recommending to people to check and do research as to how a water sample that had been in a car hours could then sit in a bag on a counter and still give an accurate DO reading. Needless to say, now he tells them they are low on iodine instead . With that said, I have a friend that has a $700 dissolved oxygen meter. It is accurate at a temperature of 80 degrees, +/- 1 point. My system at the shop, which is heavily stocked, with driftwood and sand in the tanks, usually reads at saturation, with no additional circulation, even in the bottom 4 inches of the tanks. Adequate flow, water changes, and reasonable stocking levels will usually make DO less of a concern than lower levels while there are parasites present. Until I bought a microscope and spent hours trying to describe the different cooties I was seeing, I had no idea how many parasites most fish are carrying in their gills.

Barbie

So you are right about Ich, chilodonella, and oodinium being hard to detect. I have necropsied and done gill clippings on several of the chubbies and do not beleive those to be an issue at this time. Also, a very poor indicator but somewhat of an indicator, I have some relatively fragile stock that is doing very well housed with them. SO I admit there is the possibility for parasties, I do not beleive it is the case here. My quarantine protocol is nothing special but overall sufficient. I use salt and two courses of prazi and make sure they are doing well and then they can join the ranks.
Also interesting enough, I found my smallest chubby pleco looking terrible last night, breathing heavy and sunken eyes. So I threw him in the 26 with the Lei and within 30 minutes was breathing much easier. Also the eyes popped back out this morning. Therefore I am leaning towards oxygen in this case

A while ago I lost one L14 grow out kind of out of the blue. Which I that was due to parasites. I thought I was going to loose a second and was ready to formalin fix him and send him for histopathology, but lucky it never happened. I am pretty sure that was gill flukes. This was a different tank and different fish. I share equiptment between tanks, so always possible.

Hi all,

If you have two inches of gravel (like so many aquarists have!), then small bits of food and faeces will slowly accumulate and suck up oxygen as they decompose. Better to have a thin layer of grit/sand, and vacuum regularly. Much cleaner this way. Same goes for filters. Regularly clean them. I noticed my L260s were breathing heavily last night. I suspect it's because I've been feeding them a lot recently, and not cleaned the filter in a while.

Easy to do, I think we've probably all been there. That is why I like plants, a sand substrate, a pre-filter sponge on the intake of the filter, and a regular syphon. If you see low water flow etc it only takes a minute to clean the pre-filter. If you don't have the pre-filter, the temptation is to leave opening the filter until you have more time, with potentially disastrous results.

So I threw him in the 26 with the Lei and within 30 minutes was breathing much easier. Also the eyes popped back out this morning. Therefore I am leaning towards oxygen in this case

That is one easy way to tell if you have problems with low DO or a high CO2/DO ratio, as long as you catch it in time, recovery is really quick when the fish is placed back into higher DO levels.

We have a local shop that regularly told people that their fish deaths were due to low dissolved oxygen in their saltwater systems. It took a year or so of me recommending to people to check and do research as to how a water sample that had been in a car hours could then sit in a bag on a counter and still give an accurate DO reading.

Yes, any dissolved gases are really difficult to test for. I use the planted tanks in the lab. (during the photo-period), as a quick test of whether the DO meter membranes are damaged. If the meter doesn't fairly quickly equilibrate to about 8mg/l, the membrane is damaged (at about £120 a pop).

cheers Darrel

Although I have little in the way of helping you solve your concerns, I would like to share my similar "chubby" observations.

I house three of these fish, each at approximately 3 inches in length. They've been with me for about 2 1/2 months and have also maintained a frighteningly rapid respiratory rate for the entirety of their time with me.

These fish are housed in a 55g aquarium with a pair of 9" L160 plecos, one 6" Crenicichla cyclostoma, and a group of 3" Retroculus lapidifer. The aquarium is kept at approximately 80 degrees F and is filtered by way of a built-in overflow and trickle filter which is so large that it had to be placed within the stand during its construction, as it won't even begin to fit through the doors or rear of the stand. As I'm not currently home and cannot recall the model of my return pump, I cannot quote the exact flow rate. What I can say is that the water return from the sump is aimed along the surface of the aquarium water and keeps the surface very briskly churning and provides a visible current throughout the aquarium. Additionally, my water changes are automated and consist of approximately 50 gallons of aged tap water being added to the system while allowing the system to overflow into a drain, twice weekly. This water is run through a carbon block prior to entering the aquarium. I spot-check the nitrate levels and always find that they don't even register on my test strips.

The behavior of my Parancistrus is such that they strongly prefer to remain near-to or within a small tangle of driftwood within the aquarium. At feeding time, they become noticeably excited and actively feed upon food-bits that drift near them in the strong aquarium current. These food bits, which are generally intended for the other inhabitants, include brine shrimp and finely diced pieces of mussel. Before lights-out, I place a skewered piece of zucchini within their driftwood tangle. They demolish this zucchini and have nice rounded abdomens, the following morning.

What I think I know:
- Unlikely to be infectious (at least not transmissible), as no other fish in the aquarium have adopted this behavior.
- Very unlikely to be water parameters (oxygenation, pH, nitrate, temp, or anything else), since all fish in this aquarium are Rio Tocantins rapids-dwellers (i.e. all tankmates are native to the exact same waters) and are thriving. Anyone familiar with Retroculus, is probably aware of their notorious insensitivity to low dissolved oxygen levels and other neglectful husbandry. The other fish in this aquarium are absolutely thriving.
- Despite the tachypnea, the chubbies seem otherwise healthy, based on their vigorous feeding habits.

Other considerations:
- When these fish arrived via FedEx in early December, they were in very rough condition. The temp of the transport water was in the low 60s (F). Of the eight sent to me, one was DOA, a couple others died shortly thereafter, and another a couple others lingered for a variable length of time with a strange white epidermal lesion, which appeared to result in their demise.

I am aware that my observations lack much objective data (water parameter measurements). Due to inaccuracies in testing methods and our often-inept ability to appropriately apply these measurements (assumptions about native water conditions, accepting what others have documented as factual, etc.), and my laziness, I often feel more-comfortable using comparative information (tankmate behavior, especially when from the same environment within the same water system/river).

So, I find it plausible that these fish could have suffered some degree of permanent damage, such as to their gills, from the obviously traumatic shipping. Despite saying this, I do realize that there are plenty of other physiologic reasons to have an increased respiratory rate (i.e. compensation for a metabolic acidosis, etc.). Alternatively, could this be a normal, albeit surprising, physiologic trait? Given others' observations of this pleco with a typical-appearing respiratory rate, I have trouble believing that this tachypnea is "normal" for the chubby.

I doubt any of the above is particularly helpful. Even so, I wanted to keep the dialogue alive.

nandusnandus wrote:Although I have little in the way of helping you solve your concerns, I would like to share my similar "chubby" observations.

I house three of these fish, each at approximately 3 inches in length. They've been with me for about 2 1/2 months and have also maintained a frighteningly rapid respiratory rate for the entirety of their time with me.

These fish are housed in a 55g aquarium with a pair of 9" L160 plecos, one 6" Crenicichla cyclostoma, and a group of 3" Retroculus lapidifer. The aquarium is kept at approximately 80 degrees F and is filtered by way of a built-in overflow and trickle filter which is so large that it had to be placed within the stand during its construction, as it won't even begin to fit through the doors or rear of the stand. As I'm not currently home and cannot recall the model of my return pump, I cannot quote the exact flow rate. What I can say is that the water return from the sump is aimed along the surface of the aquarium water and keeps the surface very briskly churning and provides a visible current throughout the aquarium. Additionally, my water changes are automated and consist of approximately 50 gallons of aged tap water being added to the system while allowing the system to overflow into a drain, twice weekly. This water is run through a carbon block prior to entering the aquarium. I spot-check the nitrate levels and always find that they don't even register on my test strips.

The behavior of my Parancistrus is such that they strongly prefer to remain near-to or within a small tangle of driftwood within the aquarium. At feeding time, they become noticeably excited and actively feed upon food-bits that drift near them in the strong aquarium current. These food bits, which are generally intended for the other inhabitants, include brine shrimp and finely diced pieces of mussel. Before lights-out, I place a skewered piece of zucchini within their driftwood tangle. They demolish this zucchini and have nice rounded abdomens, the following morning.

What I think I know:
- Unlikely to be infectious (at least not transmissible), as no other fish in the aquarium have adopted this behavior.
- Very unlikely to be water parameters (oxygenation, pH, nitrate, temp, or anything else), since all fish in this aquarium are Rio Tocantins rapids-dwellers (i.e. all tankmates are native to the exact same waters) and are thriving. Anyone familiar with Retroculus, is probably aware of their notorious insensitivity to low dissolved oxygen levels and other neglectful husbandry. The other fish in this aquarium are absolutely thriving.
- Despite the tachypnea, the chubbies seem otherwise healthy, based on their vigorous feeding habits.

Other considerations:
- When these fish arrived via FedEx in early December, they were in very rough condition. The temp of the transport water was in the low 60s (F). Of the eight sent to me, one was DOA, a couple others died shortly thereafter, and another a couple others lingered for a variable length of time with a strange white epidermal lesion, which appeared to result in their demise.

I am aware that my observations lack much objective data (water parameter measurements). Due to inaccuracies in testing methods and our often-inept ability to appropriately apply these measurements (assumptions about native water conditions, accepting what others have documented as factual, etc.), and my laziness, I often feel more-comfortable using comparative information (tankmate behavior, especially when from the same environment within the same water system/river).

So, I find it plausible that these fish could have suffered some degree of permanent damage, such as to their gills, from the obviously traumatic shipping. Despite saying this, I do realize that there are plenty of other physiologic reasons to have an increased respiratory rate (i.e. compensation for a metabolic acidosis, etc.). Alternatively, could this be a normal, albeit surprising, physiologic trait? Given others' observations of this pleco with a typical-appearing respiratory rate, I have trouble believing that this tachypnea is "normal" for the chubby.

I doubt any of the above is particularly helpful. Even so, I wanted to keep the dialogue alive.

thank you for posting. That was very informative. Another thing I have noticed that the larger ones that where breathing fast when in my 90g are breathing at a normal rate now in my 125, which has a lot more flow and air pumps

Fascinating observations nandusnandus.

Another interesting thing is that have enormous gill openings. The only other loricariids that have these are and . From Armbruster's loricariid homepage:

In her review of the genus, Rapp Py-Daniel (1989) stated that the only time P. aurantiacus was collected was when the river had dried to isolated pools. She suggested that the large gill openings may be an adaptation to low oxygen levels. Rhinelepis similarly has large gill openings but also has a diverticulum hypothesized to act as an accessory respiratory system (Armbruster, 1998). It is possible that the expanded gill openings are not associated with respiration and may be due to some other factor such as feeding.

Thank you, Racoll. I read that excerpt at one point, too. Intuitively, if these fish do survive in hostile, poorly oxygenated pools and have evolved to tolerate such conditions, I have to believe that they should have respiratory reserve. In effect, they should be exceptionally tolerant of low levels of decreased oxygen levels in the aquarium. If I take this to heart, I then surmise that my rapid-breathers are suffering from either another environmental problem (i.e. not the oxygen level) or are simply "damaged" fish.

mcaquatic wrote: thank you for posting. That was very informative. Another thing I have noticed that the larger ones that where breathing fast when in my 90g are breathing at a normal rate now in my 125, which has a lot more flow and air pumps

I managed to acquire several more specimens two weeks ago. While the original fish remain tachypnic, the new chubbies have a slower, less-labored (i.e. normal-appearing) respiratory rate. This, along with reasoning documented in my original post, should largely eliminate the notion that environmental parameters are to blame for the high respiratory rate of my original fish. Instead, it seems as though my original chubbies are simply broken. Perhaps it isn't even directly related to their respiratory function. Could they have suffered a hepatic injury along the way and now require the elevated respiratory rate in order to aid in the clearance of ammonia? It's doubtful; I know. I'm just rambling, at this point.

racoll wrote:Fascinating observations nandusnandus.

Another interesting thing is that

Parancistrus

have enormous gill openings. The only other loricariids that have these are

Pogonopoma

and

Rhinelepis

. From Armbruster's loricariid homepage:

In her review of the genus, Rapp Py-Daniel (1989) stated that the only time P. aurantiacus was collected was when the river had dried to isolated pools. She suggested that the large gill openings may be an adaptation to low oxygen levels. Rhinelepis similarly has large gill openings but also has a diverticulum hypothesized to act as an accessory respiratory system (Armbruster, 1998). It is possible that the expanded gill openings are not associated with respiration and may be due to some other factor such as feeding.

Thanks for posting. I am almost positive this was found to be incorrect, but I can't remember where I read it. Will have to look further for it.